You don't need to use prosciutto, you can easily make this with tomatoes, onions, olive oil, and vinegar!! It makes a great guest dish in the summer.
I received a lot of tomatoes from relatives who are tomato farmers, so I thought of a simple recipe to use up the tomatoes. Onions go great with tomatoes, so I made this marinade.
You don't need to add any salt if the raw ham is already salty. You can also substitute vinegar with lemon juice.
Enjoy Japanese food around the world.